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Saturday, October 28, 2006

UWM research helps industry make stronger, lighter and cheaper alloys High performance metals could revive foundries.

Car engines that consume less energy and can keep running on low oil, lead-free plumbing fixtures, and tanks that are light enough to be airlifted, but are just as rugged as the much heavier varieties.

They sound futuristic, but these products are already realities thanks to materials that stretch the limits of performance. Called cast metal matrix composites (MMCs), they are cheaper, lighter and stronger than their original alloys. In fact, an aluminum-based MMC developed at the University of Wisconsin-Milwaukee (UWM) can replace iron-based alloys.

"These composites have many applications in the transportation, small engines, aerospace and computer industries," says Pradeep Rohatgi, a Wisconsin Distinguished Professor of Engineering who pioneered cost-effective methods of manufacturing these composites.

Now more than a 100-million-a-year industry themselves, MMCs have been used in components for train brakes, thermal management devices in computers, and even the space shuttle and the Hubble Space Telescope.

MMCs are engineered by combining metal with a totally different class of material, such as ceramics and recycled waste. Incorporating the two materials – the matrix and the reinforcement materials – result in amazing structural and physical properties not available in the natural world.

But MMCs would not have risen so far so fast without the research of Rohatgi, who currently is developing innovations such as composites embedded with nanoparticles that can deliver qualities such as self-lubrication, abrasion-resistance and energy-absorbing capabilities. He is also creating a robust "metallic syntactic foam."

"One thing that has surprised me over the years is how easy it was to make these materials," he says.

It was Rohatgi's adaptation of a conventional foundry process to synthesize aluminum and graphite that slashed the cost of mass-producing MMCs and allowed for more complex shapes to be made.

Since then, his laboratory has done extensive work in reinforcing aluminum with elements such as graphite and silicon carbide particles (ceramics) to form materials that are 20 to 40 percent stronger. The aluminum embedded with graphite also self-lubricates, making it particularly valuable for use in engines.

Standard aluminum pistons and cylinders can stick together during a cold-engine startup or when an engine needs oil, he says. But if the parts are made from an aluminum-graphite composite, the engine is partially protected from seizing.

This year, his lab received a half million dollars in federal money to develop lighter, heavy-duty materials to meet the U.S. Army's need for vehicles that can be airlifted and operate for prolonged periods without refueling.

For all the work he has done with major car companies and Wisconsin partners like Oshkosh Truck Corp., Rohatgi says the largest users of MMCs have not been in transportation, but in the computer industry.

Computer applications require smaller volumes and they often have the money to invest in new technologies, he says. "You look for the big bang in one area and it happens in another."

The newest class of MMCs that his lab is developing fortifies aluminum with nanoparticles to produce materials that can withstand enormous amounts of stress, are exceptionally hard, but are also lightweight. Nanoparticles are smaller than 100 nanometers (about the size of a baseball shrunk to one-millionth of its original size) that sometimes behave differently than larger particles.

A nanostructured aluminum can be 10 times stronger than conventional aluminum alloys.

A third kind of MMC Rohatgi is working on turns metals into foam.

Unlike Styrofoam, in which air is pumped into a plastic matrix, syntactic (metallic) foam is filled with hollow micro-balloons set into a metal base. The tiny balloons are made from recycled "fly-ash"-- waste materials generated by coal-burning power plants – and they house either various gases or are a vacuum inside.

"The cells are smaller and more regular than air bubbles, which make them better at energy absorption, in the case of a car crash, and also useful at sound dampening," he says. "They are also very light and there may be an interest in aluminum foam in homeland security issues. It can make buildings, including bomb shelters, more blast-proof and fire-resistant."

Now in his 20th year at UWM, Rohatgi continues to help foundries, such Eck Industries in Manitowoc, diversify their business with MMC casting, giving them a defense against competition from other countries where labor is cheaper.

His lab is researching techniques that will enable industries to manufacture composite components with increased speed – and the new technology will taking the process out of the factory, making on-site manufacture of parts possible.

The U.S. military also is interested in developing the capability of quickly producing replacement parts for vehicles while on the battlefield. Rapid manufacturing technologies can be expanded to include lightweight materials for bone replacement implants and tissue scaffolds, says Rohatgi, improving the treatment of wounded soldiers in mobile environments.

"The only way to keep foundries viable is to help them develop fast-track technologies to manufacture components from advanced lightweight materials," Rohatgi says. "It gives old-line manufacturing the means to producing high-tech products."

Sunday, October 22, 2006

CHAMPAIGN, Ill. — Superconducting wires are used in magnetic resonance imaging machines, high-speed magnetic-levitation trains, and in sensitive devices that detect variations in the magnetic field of a brain.

Eventually, ultra-narrow superconducting wires might be used in power lines designed to carry electrical energy long distances with little loss.

Now, researchers at the University of Illinois at Urbana-Champaign not only have discovered an unusual phenomenon in which ultra-narrow wires show enhanced superconductivity when exposed to strong magnetic fields, they also have developed a theory to explain it.

Magnetic fields are generally observed to suppress a material’s ability to exhibit superconductivity – the ability of materials to carry electrical current without any resistance at low enough temperatures. Deviations from this convention have been observed, but there is no commonly accepted explanation for these exceptions, although several ideas have been proposed.

As reported in the Sept. 29 issue of Physical Review Letters, U. of I. physics professor Alexey Bezryadin (pronounced BEZ-ree-ah-dun) and his research group have studied the effect of applying a magnetic field to ultra-narrow superconducting wires only a few hundred atoms across, and have used a microscopic theory proposed by physics professor Paul Goldbart and his team to explain the results.

"My group discovered that magnetic fields can enhance the critical current in superconducting wires with very small diameters,” Bezryadin said. “We spoke with many colleagues and reached the consensus that this phenomenon is indeed curious.”

Magnetic fields have long been known to suppress superconductivity by raising the kinetic energy of the electrons and by influencing the electron spins. Magnetic atoms, if present in the wires, also inhibit superconductivity.

Nevertheless, as reported in the Sept. 15 issue of Europhysics Letters, Goldbart, postdoctoral researcher Tzu-Chieh Wei and graduate student David Pekker proposed that the enhancement observed by Bezyradin’s group was due to magnetic moments in the wires.

“Even though the two effects – magnetic fields and magnetic moments – work separately to diminish superconductivity, together one effect weakens the other, leading to an enhancement of the superconducting properties, at least until very large fields are applied,” Goldbart said.

As for the origin of these magnetic moments, the collaborating groups proposed that exposure of the wires to oxygen in the atmosphere causes magnetic moments to form on the wire surfaces. On their own, the moments weaken the superconductivity, but the magnetic field inhibits their ability to do this. This effect shows up in ultra-narrow wires because so many of their atoms lie near the surface, where the magnetic moments form.

With postdoctoral research associate Andrey Rogachev (now a physics professor at the University of Utah) and graduate student Anthony Bollinger, Bezryadin deposited either niobium or an alloy of molybdenum and germanium onto carbon nanotubes to fabricate wires that were less than 10 nanometers wide. The superconductivity of these wires under a range of applied magnetic fields was examined, and the experimental results were compared with the proposed theory, revealing an excellent correlation between the two.

"The results of this work may provide a key to explaining our previous findings that nanowires undergo an abrupt transition from superconductor to insulator as they get smaller,” said Bezryadin, referring to work published in the Sept. 27 issue of Europhysics Letters.

The work was funded by the U.S. Department of Energy and the National Science Foundation.

Wednesday, October 18, 2006

Pacific Northwest National Laboratory scientists first to measure electrical charge shuttled by proteins removed from living cells

Caption: Artist's depiction of purified, electrified bacterial cell outer membrane protein binding with and passing electrons to the iron-rich mineral hematite. In this purified-protein fuel cell, the seal made by the protein coating on the electrode effectively acts in place of a membrane necessary in whole-organism biofuel cells.

Eliminating the membrane could aid the design of bioreactors to power small electronic devices. Credit: Pacific Northwest National Laboratory, Usage Restrictions: None.

RICHLAND, Wash. – Proteins keep cells humming. Some are enzymes that taxi electrons to chemicals outside the cell, to discharge excess energy generated during metabolism. This maintains energy flow in the cell and, in turn, keeps the cell alive.

The process has worked a little like that slogan for a hyper-electrified desert gambling town: What happens in the cellular environs stays there.

Now, scientists for the first time have observed this electricity-shuttling process taking place sans cells, in purified proteins removed from the outer membrane of the versatile, metal-altering soil bacterium Shewanella oneidensis. Reporting in the current advance online edition of the Journal of the American Chemical Society, they suggest that proteins rendered portable from the organisms that spawned them could make miniature bioreactor cells feasible.

"We show that you can directly transfer electrons to a mineral using a purified protein, and I don't think anyone had shown that before," said Thomas Squier, senior author and lab fellow at the Department of Energy's Pacific Northwest National Laboratory.

The feat is the bacterial equivalent of removing lungs and coaxing the disembodied tissue to breathe.

Squier and principal authors Yijia Xiong and Liang Shi, PNNL staff scientists, discovered that the proteins, outer membrane c-type cytochrome A, or OmcA, formed a dense coating on the iron-rich mineral hematite. The metal in the mineral acts as an "acceptor," or dumping point, for thousands of trillions of electrons per square centimeter shuttled by the OmcA-donor. The function is a relic of respiration, in which the cell depends on the protein to dump electrons to maintain a steady flow of energy and prevent the organism-damaging accumulation of electrons.

PNNL staff scientist and co-author Uljana Mayer devised new tagging methods that enabled the team to isolate sufficient amounts of protein. The tags also allowed fast measurements of protein-mineral binding.

The researchers supplied the protein with energy--directly as electrons or in the form of a natural cellular fuel called NADH--and only during binding detected charge-transfer from protein to mineral, through a combination of techniques that included FCS, or fluorescent correlation spectroscopy, and confocal microscopy. These yielded a "fluorescence intensity trace" whose brightness depended entirely on whether hematite was available to bind with OmcA in solution. No hematite, dim; hematite, bright.

How bright?

"The peak current, or flux, doesn't run long, just a few seconds," Squier said, "but flux is at least as good as what you would find in the most efficient bioreactors, which rely on living bacteria."

Biological fuel cells, or biofuel cells, are not yet powerful enough to be commercially viable but they offer the promise of breaking down sewage and other biological waste while generating electricity directly from the same process. An example, Squier said, is a self-powering sewage treatment plant.

Using pure protein opens up the possibility of shrinking biofuel cells to power small electronic devices, Squier said. Whole-organism biofuel cells require engineers to design a space-adding membrane that prevents unwanted reactions between fuel, the charge-transporting agent and the electron-accepting metal, the latter being the electrode that carries the electricity to the device. In purified protein fuel cells, the seal made by the protein coating on the electrode effectively acts in place of the membrane. ###

Squier and colleagues performed the work with a team at PNNL and colleagues at the PNNL-based W.R. Wiley Environmental Molecular Sciences Laboratory biogeochemistry grand challenges program.

PNNL is a DOE Office of Science laboratory that solves complex problems in energy, national security, the environment and life sciences by advancing the understanding of physics, chemistry, biology and computation. PNNL employs 4,200 staff, has a $725 million annual budget, and has been managed by Ohio-based Battelle since the lab's inception in 1965.

Sunday, October 15, 2006

BLACKSBURG, VA., September 10, 2006 -- Fuel cells have been a workable technology for decades – but expensive and lacking in infrastructure. In recent years, researchers have addressed durability, manufacturability, and conductivity challenges in alternative proton exchange membrane (PEM) materials for fuel cells – bringing the hydrogen-based energy source closer to reality.

James McGrath, University Distinguished Professor of Chemistry with the Macromolecules and Interfaces Institute at Virginia Tech, will announce his research group’s latest development, a PEM material that retains conductivity during low humidity, during his plenary lecture at the Challenges for the Hydrogen Economy symposium during the the 232nd National Meeting of the American Chemical Society (ACS) on Sept. 10 - 14 in San Francisco.

Fuel cells convert chemical energy, usually from hydrogen, to electrical energy. In a PEM fuel cell, the critical exchange takes place through a thin water-swollen copolymer film that contains sulfonic acid (SO3H) groups. Electrons are peeled off by oxidation of the hydrogen atoms and hydrated protons pass through the film to combine with oxygen on the other side to form water as a byproduct.

The efficiency of the exchange process depends upon water, so efficiency – measured as proton conductivity – goes down as humidity goes down. “Up to now, a lot of water has been needed to assist the proton transfer process,” said McGrath. “But, in the desert, that is pretty inefficient.” McGrath, chemical engineering Professor Don Baird, and their students demonstrated a method for creating a material with improved conductivity even at lower humidity. The U.S. Department of Energy awarded McGrath and Baird’s groups $1.5 million over five years to advance the research.

Instead of stirring two kinds of reactive monomers, or small molecules, together to form a new random copolymer, the new material links blocks of two different short polymers in sequences. For example, he would link polymer W (loves water) and polymer d (dry but strong) into a chain this way: WWWWWdddddddWWWWWdddddddd.

The researchers can link a 10- to 50-unit block of a polymer containing acidic groups (SO3H) that like water (hydrophilic) to an equally long block of a polymer that has mechanical strength, thermal stability, and endurance, but hates water (hydrophobic). The chains self-assemble into flexible thin films. Under an atomic force microscope, the film’s swirling surface looks like a fingerprint, with light ridges and dark channels. It turns out that the soft hydrophilic polymer forms the dark channels where water is easily absorbed so that the entire film – or proton exchange membrane (PEM) – has an affinity for water transport that is two to three times higher than the present commercially available PEM.

In addition to making PEM materials with better qualities, another goal of the research is to make PEM materials that can be easily manufactured. The self-assembling nature of the block copolymer material into a nanocomposite film is an important attribute. In addition, Baird is working on processing the film from powders using a reverse roll coater, equipment commonly available in the coatings industry but not yet being used to produce PEM material. McGrath will present the paper, “Progress in alternate proton exchange membrane materials for fuel cells (Fuel 3),” at 10:15 a.m., Sunday, Sept. 10, in the Golden Ballroom of the Sheraton Palace.

Graduate students in McGrath’s group will present details regarding the alternative PEM materials during the Division of Fuel Chemistry symposium. The first public presentation of most of the atomic force microscope images of the new polymer will be during a presentation by Virginia Tech graduate student Anand Badami. The paper, Morphological analysis of molecular weight effects based on random and multiblock copolymers for fuel cells, is coauthored by fellow graduate students in Virginia Tech’s macromolecular science and engineering program Hae-Seung Lee, Yanxiang Li, Abhishek Roy, and Hang Wang, and McGrath.

Friday, October 13, 2006

"I am Kai, last of the Brunnen-G. Millennia ago, the Brunnen-G led humanity to victory in the war against the insect civilization. The Timeprophet predicted that I would be the one to destroy the divine order in the league of the 20.000 planets. Someday that will happen, but not today. Cause' today is my day of death. The day our story begins." - LEXX

Researchers at the National Institute of Standards and Technology (NIST) have made the first confirmed "spintronic" device incorporating organic molecules,

a potentially superior approach for innovative electronics that rely on the spin, and associated magnetic orientation, of electrons. The physicists created a nanoscale test structure to obtain clear evidence of the presence and action of specific molecules and magnetic switching behavior.

Whereas conventional electronic devices depend on the movement of electrons and their charge, spintronics works with changes in magnetic orientation caused by changes in electron spin (imagine electrons as tiny bar magnets whose poles are rotated up and down). Already used in read-heads for computer hard disks, spintronics can offer more desirable properties--higher speeds, smaller size--than conventional electronics. Spintronic devices usually are made of inorganic materials. The use of organic molecules may be preferable, because electron spins can be preserved for longer time periods and distances, and because these molecules can be easily manipulated and self-assembled. However, until now, there has been no experimental confirmation of the presence of molecules in a spintronic structure. The new NIST results are expected to assist in the development of practical molecular spintronic devices.

The experiments, described in the October 9 issue of Applied Physics Letters,* used a specially designed nanoscale "pore" in a silicon wafer. A one-molecule-thick layer of self-assembled molecules containing carbon, hydrogen and sulfur was sandwiched in the pore, between nickel and cobalt electrodes. The researchers applied an electric current to the device and measured the voltage levels produced as electrons "tunneled" through the molecules from the cobalt to the nickel electrodes. (Tunneling, observed only at nanometer and atomic dimensions, occurs when electrons exhibit wave-like properties, which permit them to penetrate barriers.)

The pore structure stabilized and confined the test molecules and enabled good molecule-metal contacts, allowing the scientists to measure accurately temperature-dependent behavior in the current and voltage that confirm electron tunneling through the molecular monolayer. Some electrons can lose energy while tunneling, which corresponds to vibration energies unique to the chemical bonds within the molecules. The NIST team used this information to identify and unambiguously confirm that the assembled molecules remain encapsulated in the pore and are playing a role in the device operation. In addition, by varying the magnetic field applied to the device and measuring the electrical resistance, the researchers identified magnetic switching in the electrodes from matching to opposite polarities. ###

This work was supported in part by the Defense Advanced Research Projects Agency.

Sunday, October 08, 2006

A team of researchers has received a four-year, $1 million grant from the National Science Foundation to study improved methods for biological separations. Led by Ravi Kane, the Merck Associate Professor of Chemical and Biological Engineering at Rensselaer Polytechnic Institute, the group plans to develop nanoscale surfaces that actively reassemble in the presence of DNA, which could eventually lead to more efficient separation tools for genomics and proteomics.

The researchers are taking their inspiration from nature, mimicking the very membranes that surround our cells to create platforms for separating biological molecules. These "lipid bilayers," which are made up of two opposing layers of fat molecules, act as the cell's barrier to the outside world. DNA molecules move on these surfaces in two dimensions, much like objects on a conveyor belt. Kane and his colleagues recently discovered that the mobility of DNA molecules is closely coupled to the movement of the underlying lipid bilayer.

"The advantage of these surfaces is that they can be actively modified," Kane said. "Thus by changing the temperature, shining light, or applying an electric field, we propose to change the behavior of the surfaces." In one approach, Kane and his colleagues are building a molecular obstacle course made up of nanoscale domains. When an electric field is applied at one end, DNA molecules will move across the surface and collide with the obstacles, impeding their motion. The researchers have already made surfaces on which they can control the size and positioning of obstacles; next, they plan to test the movement of DNA.

The overarching goal is to understand how biological molecules of all types move across the surface of lipid bilayers. "This particular project is focused on DNA, but the approach could potentially be used for separating other biological molecules, such as proteins," Kane said. He envisions immediate applications in genomics and proteomics, with the new approach providing several improvements over current techniques.

The new surfaces could yield separations with higher resolution and greater efficiency, Kane suggested. And they can be easily fabricated in a normal laboratory, whereas other surfaces require the use of a clean room. The nanoscale surfaces are also dynamic, while the materials in use today cannot be altered once they have been made.

In the more distant future, the surfaces could even be used as biosensors or to deliver DNA molecules for gene therapy applications, Kane said. ###

The funding is part of a National Science Foundation program to develop Nanoscale Interdisciplinary Research Teams (NIRT) to catalyze synergistic research and education in emerging areas of nanoscale science and technology.

Other researchers involved with the project include Professor Steve Granick at the University of Illinois at Urbana-Champaign, Professor Sanat Kumar at Columbia University, Professor Omkaram Nalamasu at Rensselaer, and Chakradhar Padala, a doctoral student in chemical and biological engineering at Rensselaer.

About Rensselaer, Rensselaer Polytechnic Institute, founded in 1824, is the nation's oldest technological university. The university offers bachelor's, master's, and doctoral degrees in engineering, the sciences, information technology, architecture, management, and the humanities and social sciences. Institute programs serve undergraduates, graduate students, and working professionals around the world.

Rensselaer faculty are known for pre-eminence in research conducted in a wide range of fields, with particular emphasis in biotechnology, nanotechnology, information technology, and the media arts and technology. The Institute is well known for its success in the transfer of technology from the laboratory to the marketplace so that new discoveries and inventions benefit human life, protect the environment, and strengthen economic development.

chemical vapor deposition is intercalated with copper to create a composite which exhibits good thermal properties ideal for chip cooling. Photo: NASA Ames Center for Nanotechnology

SYDNEY - 28th Sept 2006 - Marking a major milestone in the delivery of Nanotechnology related information; AZoNetwork and Nanotechnology Victoria (NanoVic) today announced the official release of the first in a series of Nanotechnology Reviews in a Podcast format.

This initial Podcast provides a short history of the development of Nanotechnology and interviews several key players from within the Nanotech industry, research community and government to draw out their current views on the likely impact Nanotechnology will have on healthcare, materials and the environment.

Dr. Peter Binks, CEO of NanoVic (Melbourne) commented, "We believe this form of new media is an ideal fit with our role of spreading the word of Nanotechnology to the general public, industry and academia".

"We are very excited to have worked on this project with the team at AZoNano.com as the global footprint of AZoNano.com and the 300,000 monthly visitor sessions it receives means it is the ideal launch platform for a Podcast such as this".

Dr. Ian Birkby, the CEO of AZoNetwork (Sydney) the operator of the AZoNano.com website commented, "There is a real need to make Nanotechnology more accessible to the world outside the community of Nanotech specialists. We believe that the support we've received from NanoVic has enabled us to produce the first in series of Nanotech podcasts that will ensure the issues around Nanotechnology are accessible to all"

"We also believe that in a world where our working lives are highly time pressured, the ability to spend 30 mins during your drive to work listening to the latest developments in Nanotech emphasizes the potential of the Podcasting medium in relation to nanotechnology."

The Podcast provides an overview of nanotechnology and includes interviews with the following key players;

Gavin Rezos - Former Managing Director and now Consultant to PsiVida, a leading player in the use of BioSilion in the targeted delivery of drugs for the treatment of cancer.

Dr. Jackie Fairley - CEO, Starpharama, a leading NanoBiotech company at the forefront of the use of dendrimer technology for the treatment of HIV and genital Herpes.

Dr. Sarah Morgan - Project Manager - Delivery & Sensing at Nanotechnology Victoria Ltd. Sarah leads commercial projects in the development and testing of analytical and delivery devices, with a focus on water analysis and environmental applications.

Dr. Terry Turney - Director of the CSIRO Nanotechnology Centre. Terry is at the forefront of Australian Government initiatives relating to the commercialisation of Nanotech products

Professor Frank Caruso - Professor and Federation Fellow in the Department of Chemical and Biomolecular Engineering at the University of Melbourne. A leading researcher in the development of "bottom up" Nanotechnology as applied to Polymeric layers

Dr. Kristin Alford, currently the Marketing Director at Nanotechnology Victoria. Kristin is also the Director of Bridge8 Pty Ltd which she established in 2002 to consult to a range of organisations on foresight, strategy and planning.About AZoNetwork, AZoNetwork owns and operates azom.com/ - The A to Z of Materials, azonano.com/ - The A to Z of Nanotechnology, azobuild.com/ - The A to Z of Building and Construction related technologies and news-medical.net/ - The A to Z of medical news.

Based in Sydney Australia the company was founded in April 2000 and currently serves over 2.4 million monthly visitors sessions from the engineering, science, construction and medical sectors. azonetwork.com

About Nanotechnology Victoria (Nanovic), Nanotechnology Victoria Ltd (Melbourne Australia) is nanotechnology commercialisation company formed by four major research providers, with funding from the Victorian Government. It has a portfolio of investments and licenses in nanomaterials and bionano developments, and is a leading contributor to education and public awareness of nanotechnology in Australia. nanovic.com.au